The present invention relates to a multiple charged developing gun which applies an electrical charge by forming a multiple charged electrode portion that is made of plural electrodes.
In the prior art, the process for forming a phosphor face on CRT panels includes the applying of a black matrix which entails the steps of washing panel, application polymeric conductor and photoconductor layer, charging, exposure, black matrix developer, and fuser. Next, the process for forming a phosphor face includes the following steps for applying a phosphor material: P.C. charging, G exposure, G developer, fuser, P.C. charger, B exposure, B developer, fuser, R exposure, R developer, fuser. In this way, phosphor material comes to be applied through a method of electrophotographically manufacturing a screen assembly.
In the above process of forming a black matrix and each of the R, G, B phosphor materials through a method of electrophotographically manufacturing a screen assembly, the developing apparatus of the prior art includes: a body; a panel fixing portion placed on the upper part of the body; a developing gun that is a cylinder shaped and a strip type electrode is placed in the middle of the exit; a powder supply line which supplies powder for black matrix or R, G, B phosphor material (hereinafter referred to as just powder); a powder supply apparatus, connected to the powder supply line; an air supply line that supplies air to the developing gun and is installed separately from the powder supply line; an air supply apparatus connected to the air supply line; and an electric supply apparatus which supplies electricity to the strip type electrode inside the developing gun. The structure of the above panel fixing portion is formed so that it grounds the panel it secures.
In the above formation of the prior art developing apparatus, when the CRT panel, which is positively charged and is exposed, is fixed to the panel fixing portion, the powder supply apparatus and the air supply apparatus start operating, and through the powder supply line and the air supply line, powder and air is supplied to the developing gun and the electricity supply apparatus provides electricity to the electrodes of the developing gun.
The powder, which by following the flow of the air that is supplied to the developing gun gets sprayed out from the developing gun. While being forced out, the powder is electrically charged (to the same positive pole as the panel) by the corona discharge of the electrode fixed to the exit of the developing gun.
The panel fixed to the panel fixing portion has formed, an electrical line through the charged and un-charged portion. This is realized because the charged portion and the un-charged portion are formed in a determined pattern by the operations of charging and exposure, and because the conduction layer is grounded by the panel fixing portion. As a result, the powder, which is charged to the same pole as the panel and shot out of the developing gun, follows the electrical line and adheres to the un-charged portion and is developed in a determined pattern.
When using the prior art developing apparatus composed as in the above, because the powder sprayed through the developing gun is charged by the strip type electrode, the charged efficiency is diminished and an electric pole opposite to the electric pole charged on the panel exists. The powder having the opposite electric pole is adhered to a charged portion which developing is not necessary. Hence, it causes mixed colors and indistinct pictures. Namely, when developing the phosphors in the order of G--B--R, when G phosphor is developed, the mixed colors appear on the portion developing G or R phosphor because of adherence of G phosphor thereon. Furthermore, when developing the black matrix, it causes indistinct pictures that the powder is adhered on the portion which each phosphor is developed. In addition, powder charged to the opposite pole on the panel cohere with the powder charged to the same pole on the panel. Accordingly, because the size of the powder cohered is about 100 .mu.m and they are adhered on the surface of the panel, the phosphor surface is not equal.